Field of the Invention
The present disclosure relates to a display device, and more particularly, to an organic light emitting display device and a method of manufacturing the same.
Discussion of the Related Art
Examples of flat panel display (FPD) devices include liquid crystal display (LCD) devices, plasma display panels (PDPs), electrophoretic display (EPD) devices, organic light emitting display devices, etc. Recently, organic light emitting display devices are being widely used as one type of FPD device.
In such display devices, the organic light emitting display devices are self-emitting devices and have low power consumption, a fast response time, high emission efficiency, high luminance, and a wide viewing angle, thereby attracting attention as next-generation display devices.
Particularly, organic light emitting display devices each including an organic light emitting layer formed of a material having a soluble characteristic is being recently developed for increasing the convenience and efficiency of a process of manufacturing the organic light emitting display devices.
FIG. 1 is a schematic cross-sectional view of a related art soluble organic light emitting display device.
As shown in FIG. 1, a planarization layer 1, an anode electrode 2, a bank 3, an organic light emitting layer 5, and a cathode electrode 6 are sequentially provided on a substrate.
The planarization layer 1 planarizes a thin film transistor (TFT) layer provided on the substrate, and the anode electrode 2 is provided on the planarization layer 1.
The bank 3 is provided on the anode electrode 2 and defines a pixel area. The bank 3 is provided on each of one side and the other side of the anode electrode 2 to expose an upper surface of the anode electrode 2. The bank 3 is formed of an organic material.
The organic light emitting layer 5 is provided in the pixel area defined by the bank 3, and the cathode electrode 6 is provided on the organic light emitting layer 5.
In detail, in the soluble organic light emitting display device, in order to increase the convenience and efficiency of a manufacturing process, an organic light emitting material having a soluble characteristic is sprayed or dropped on the pixel area defined by the bank 3 through an inkjet printing process, and then, by curing the organic light emitting material, the organic light emitting layer 5 is formed.
Particularly, in order for the organic light emitting material not to flow out into an adjacent pixel area, an upper surface of the bank 3 is formed to have a hydrophobic characteristic. That is, in the soluble organic light emitting display device, the bank 3 restricts an area where the organic light emitting layer 5 is provided, so that the organic light emitting material is well collected in only a corresponding pixel area.
The related art soluble organic light emitting display device has the following problems.
As described above, after the bank 3 including an organic material is formed, the organic light emitting layer 5 and the cathode electrode 6 are formed on the anode electrode 2. However, as illustrated in FIG. 1, a residual layer including an organic material or a foreign material D remains on the anode electrode 2 in a process of forming the bank 3. Also, the residual layer including the organic material or the foreign material D obstructs a movement of a hole from the anode electrode 2, causing the reduction in lifetime of the organic light emitting display device and the degradation in performance.
In order to solve such a problem, in the related art organic light emitting display device, surface treatment technology using plasma or extreme ultraviolet (EUV) is used for removing the residual layer including the organic material or the foreign material D after the bank 3 is formed. However, a hydrophobic area of the upper surface of the bank 3 is simultaneously removed by the surface treatment technology. For this reason, the upper surface of the bank 3 does not have a hydrophobic characteristic, and consequently, a unique function of the bank 3 for restricting the area where the organic light emitting layer 5 is provided is not realized.
Moreover, since the residual layer including the organic material or the foreign material D remains on the upper surface of the anode electrode 2, the upper surface of the anode electrode 2 has a rough surface, and for this reason, the organic light emitting layer 5 and the cathode electrode 6 formed on the upper surface of the anode electrode 2 are not formed to have a uniform thickness, causing the reduction in emission efficiency.